ATI Radeon HD 2900 XT Benchmarks
When you’re the lead dog, the only thing the rest of the pack sees is a bull’s-eye. And the folks behind AMD’s ATI brand have been staring at that target for more than two years.
Having failed to defeat their graphic rivals the high end, AMD has lowered its sights to focus on the middle range—the price point where they figure most people actually buy new videocards. And so today they’ve introduced the top end of their new ATI Radeon HD 2000 series: The 2900 XT. This GPU can’t compete with Nvidia’s top-end GeForce 8800 Ultra or even the slightly less-powerful GeForce 8800 GTX. No, the $400 Radeon HD 2900 XT is aimed squarely at Nvidia’s GeForce 8800 GTS.
It took a while for that message to sink in when AMD briefed us several weeks back, especially when Rick Bergman, senior vice president of the AMD Graphics Group opened his remarks with “Yes, we’ve lost market share over the past couple quarters, but you’re going to see AMD come out swinging.”
Uh, Rick, seems your bat is a wee bit small.
NICE BAT YOU GOT THERE
But when you study the HD 2900 XT, you realize there’s some pretty solid wood in it. And in terms of benchmarks, it does outrun Nvidia’s 640MB 8800 GTS. But here’s the key question: Can AMD take market share away from Nvidia without even trying to compete at the high end. After all, people tend to perceive the winner at the high end to be the winner across the board. More importantly, this quarter’s high-end product is the next quarter’s mid-range—and this quarter’s mid-range is the next quarter’s bargain. What’s AMD going to do when the much-faster 8800 GTX falls into mid-range territory?
For now, let’s see what AMD has to offer today, looking at the new chip’s architecture first and its benchmark performance second. It should surprise no one that the entire HD-2000 series features a unified shader architecture. DirectX 10 and Shader Model 4.0 all but demand it, after all, and ATI has previous experience developing this type of graphics processor (for Microsoft’s Xbox 360). This means all the chip’s stream processors (there are 320 inside the 2900 XT) can perform vertex, pixel, or geometry shading as the need arises.
The Radeon HD 2900 XT is only a trifle longer than a GeForce 8800 GTS
These components, however, are limited to operating at the same speed as the core (up to 740MHz for the 2900 XT). The 8800 GTX, in comparison, has just 128 stream processors, but they run at more than twice the speed of the core: 1.35GHz versus the core’s clock speed of 575MHz. But as we’ll see when we look at benchmark numbers, this speed trick doesn’t help the 96 stream processors in Nvidia’s 8800 GTS out-gun AMD’s 2900 XT.
AMD’s engineers have doubled the width of the ring-bus memory architecture they introduced with the Radeon X1000 series to a full 512 bits. The theory behind the ring bus is that you can speed up memory transfers by decentralizing the chip’s memory access. In AMD’s design, four “ring stops” surround the GPU; and each ring stop has two 64-bit memory channels (2x64x4=512) over which memory reads and writes can occur.